On 12/12/2012 01:35 PM, ольга крыжановская wrote:
Michal, has been any one working on the Linux kernel fifo/pipe
implementation to implement I_PEEK? Is there a Bugzilla entry for
this?
Olga
Hi Olga,
unfortunately, it's still in kernel team's todo list.
There is bugzilla for this, but it is internal only, so not public.
Michal
On Wed, Jun 13, 2012 at 5:54 PM, Michal Hlavinka <[email protected]> wrote:
On 06/05/2012 03:03 PM, Cedric Blancher wrote:
On 5 June 2012 09:11, Michal Hlavinka<[email protected]> wrote:
On 06/01/2012 02:32 PM, Irek Szczesniak wrote:
Michal, did anyone ever filed a bug against Linux's FIFO/PIPE
implementations to support I_PEEK? As far as I can check all SystemV
derivatives (including Solaris), AIX and HP/UX support I_PEEK on pipes
and fifos.
I don't know if there was any official attempt. I asked a few kernel
developers in person and they told me that no one will bother with this.
<rant>
Michal, I recall that Redhat staff once ridiculed and mocked a patch
(...why add extra performance support for a dead OS [Solaris] ...)
which added support for I_PEEK to bash2 and finally convinced the
maintainers NOT to take it. So basically this issue is blocked from
both sides, kernel and bash, by Redhat.
Why?
</rant>
I'm not aware about anything related, so I can't answer your
ran^W^W^Wquestion.
As for an implementation in the Linux fifo kernel module, the I_PEEK
ioctl() can be implemented along the lines of a read() syscall but
without disposing the data which have been read. An implementation
should therefore be very easy and should give the shells in Linux a
SERIOUS performance advantage. I'm wondering why Redhat isn't
interested in performance. Oh yes, see<rant />
Cedric was somewhat right in his reply. There are a lot of processes which
are quite resource demanding even for one line change. Also, there is always
more work than what can be done (especially on kernel side. afaik, we're
still hiring ;-) ). If someone does X, it means he won't be able to do Y.
So, we do what product management tell us to do.
Also, please don't forget that Red Hat is only Linux, but Linux is not only
Red Hat. (Well, nowadays even the first part is no longer completely true.)
I wanted to add I_PEEK feature request to upstream bugzilla, but I've been
told that it does not work that way. It'd rot there for ages until someone
would close that a few years later during some bugzilla clean up.
Anyway, I found up a few colleagues willing to code it. I need a feature
request to be filed now. I'm going to ask a few customers who complained
about 'connection reset by peer' messages if they are willing to do it. If I
fail, I'll try to convince them to code it in their spare time.
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